Efficient search space analysis for join factorization
US7809713B2 · kind B2 · utility
9Cited by
67References
22Claims
0Family size
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Key dates
| Filing date | Mar 8, 2007 |
| Grant date | Oct 5, 2010 |
| Priority date | — |
| Expiry date | Oct 29, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/24544
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Under a type of query transformation referred to herein as join factorization, the branches of an UNION/UNION ALL query that join a common table are combined to reduce accesses to the common table. The transformation can be expressed as (T1 join T2) union all (T1 join T3)=T1 join (T2 union all T3), where T1, T2 and T3 are three tables. A given query may be rewritten in many alternate ways using join factorization. Evaluating each alternative can be expensive. Therefore, the alternatives are generated and evaluated in a way that minimizes the cost of evaluating the alternatives.
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